生命周期评价方法在氧化钴生产中的应用

氧化钴生产是锂钴氧二次电池全生命周期重要阶段之一。本实验是以粗氢氧化钴为原材料,利用生命周期评价方法对氧化钴生产进行综合分析,全面评价氧化钴生产中资源、能源消耗以及环境污染物排放,并对由此产生的环境影响潜值进行量化估算。结果显示,氧化钴生产中环境潜在影响大小依次是富营养化、粉尘和烟尘、酸化、全球变暖、固体废弃物负担,其相对值依次是:24.04、22.88、4.30、3.29、1.49。根据评价结果,提出对氧化钴生产过程进行技术改造及相关材料使用更换来降低氧化钴生产对环境的影响。     

ACF负载复合金属氧化物催化还原NO的研究

为了研究活性碳纤维（ACF）负载复合金属氧化物催化还原NO的效果,采用浸渍法制备了系列负载氧化铈和氧化铜的ACF,在微型反应器中进行程序升温反应,通过正交试验,确定催化反应的最佳条件,考察了反应温度和复合金属氧化物的不同含量对催化活性的影响,并与ACF负载单金属氧化物作了比较,同时对催化剂进行了扫描电镜和傅里叶红外光谱分析实验。实验结果表明,在氨氮比是1.1∶1,氧气体积比为5%,体积流速为4 000 h^-1的条件下,负载复合金属氧化物的ACF低温活性相差很大,随着温度的升高,催化效率持续提高。当氧化铈与氧化铜的含量分别为10%和30%,在120～300℃区域内去除率维持80%以上,是低温催化中理想的催化剂。     

储氧材料负载的钴基整体式催化剂的活性研究

以Ce-Zr-Mn三组分储氧材料(OSM)和Y2 O3、ZrO2稳定的γ-Al2 O3 (YSZ-Al2 O3)为载体,制得Co基催化剂,再以不同比例的Co/OSM和Co/YSZ- Al2 O3制得堇青石为基体的Co基整体式催化剂.上述催化剂活性用甲烷催化燃烧性能进行评估.结果表明,甲烷燃烧催化活性顺序为Co/OSM≈...     

同步硝化反硝化工艺中DO浓度对N2O产生量的影响

采用序批式生物膜反应器（SBBR）,在连续曝气全程好氧的运行条件下,考察不同溶解氧浓度对同步硝化反硝化脱氮性能及N2O产量的影响。控制溶解氧浓度恒定在1、2、2.5和3 mg/L。结果表明,DO为2 mg/L和2.5 mg/L时,氨氮去除率分别为97.9%和98.5%,同步硝化反硝化率均为99%。DO为2 mg/L时,系统中N2O产生量最低,为0.423 mg/L,占氨氮去除量的1.4%;DO为3 mg/L时N2O的产生量最高,为2.01 mg/L,是DO为2 mg/L时的4.75倍。系统中亚硝酸盐的存在可能是高溶解氧条件下N2O产量增加的主要原因,同步过程中没有NOx-的积累即稳定的SND系统有利于降低生物脱氮过程中N2O的产生量。     

To duckweeds (Landoltia punctata), nanoparticulate copper oxide is more inhibitory than the soluble copper in the bulk solution

CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer-Emmett-Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6 mg L⁻¹ soluble copper or by 1.0 mg L⁻¹ CuO-NP that released only 0.16 mg L⁻¹ soluble Cu into growth medium. A significant decrease of chlorophyll was observed in plants stressed by 1.0 mg L⁻¹ CuO-NP, but not in the comparable 0.2 mg L⁻¹ soluble Cu treatment. The Cu content of fronds exposed to CuO-NP is four times higher than in fronds exposed to an equivalent dose of soluble copper, and this is enough to explain the inhibitory effects on growth and chlorophyll content.     

Chronic toxicity of ZnO nanoparticles, non-nano ZnO and ZnCl2 to Folsomia candida (Collembola) in relation to bioavailability in soil

The chronic toxicity of zinc oxide nanoparticles (ZnO-NP) to Folsomia candida was determined in natural soil. To unravel the contribution of particle size and free zinc to NP toxicity, non-nano ZnO and ZnCl₂ were also tested. Zinc concentrations in pore water increased with increasing soil concentrations, with Freundlich sorption constants K_f of 61.7, 106 and 96.4 l/kg (n = 1.50, 1.34 and 0.42) for ZnO-NP, non-nano ZnO and ZnCl₂ respectively. Survival of F. candida was not affected by ZnO-NP and non-nano ZnO at concentrations up to 6400 mg Zn/kg d.w. Reproduction was dose-dependently reduced with 28-d EC50s of 1964, 1591 and 298 mg Zn/kg d.w. for ZnO-NP, non-nano ZnO and ZnCl₂, respectively. The difference in EC50s based on measured pore water concentrations was small (7.94-16.8 mg Zn/l). We conclude that zinc ions released from NP determine the observed toxic effects rather than ZnO particle size.     

Oxidation of bisphenol F (BPF) by manganese dioxide

Bisphenol F (BPF), an environmental estrogen, is used as a monomer in plastic industry and its environmental fate and decontamination are emerging concern. This study focused on the kinetics, influencing factors and pathways of its oxidation by MnO₂. At pH 5.5, about 90% of BPF was oxidized in 20 min in a solution containing 100 μM MnO₂ and 4.4 μM BPF. The reaction was pH-dependent, following an order of pH 4.5 > pH 5.5 > pH 8.6 > pH 7.5 > pH 6.5 > pH 9.6. Humic acids inhibited the reaction at low (≤pH 5.5) and high pH (≥pH 8.6) at high concentrations. In addition, metal ions and anions also suppressed the reaction, following the order Mn²⁺ > Ca²⁺ > Mg²⁺ > Na⁺ and HPO₄²⁻ > Cl⁻ > NO₃⁻ ≈ SO₄²⁻, respectively. A total of 5 products were identified, from which a tentative pathway was proposed.     

Evaluation of PCDD/F oxidation catalysts: confronting studies on model molecules with tests on PCDD/F-containing gas stream

Titania supported vanadium oxide is a renowned catalyst for the abatement of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) from gas effluents. To develop more active formulations, researchers mainly rely on lab-scale experiments on “PCDD/Fs-mimicking substances”, like (chloro)-benzene. Using such model compounds is convenient whereas handling PCDD/Fs in the laboratory is potentially hazardous and complicated. Recent studies, however, challenged some foremost conclusions of model compound based studies, starting from the observation that different model compounds gave contrasted results. Thus the present work aims at confronting some of these dubious conclusions with direct experimental tests on PCDD/Fs. One reference V₂O₅/TiO₂ catalyst and three modified formulations (V₂O₅/TiO₂-SO₄, V₂O₅-MoO₃/TiO₂, and V₂O₅-WO₃/TiO₂) have been evaluated. A dedicated apparatus was used which allows safe and reliable tests on a mixture of PCDD/Fs congeners. Some of the previously proposed catalyst improvement strategies actually prove to be disadvantageous in the removal of PCDD/Fs. In particular, MoO₃- and WO₃-modified catalysts were significantly less active than the reference catalyst. These observations show that conclusions from model compound based studies must be drawn with care and should ideally be confronted with tests on the actual target pollutants.     

Activated carbon/Fe(3)O(4) nanoparticle composite: fabrication, methyl orange removal and regeneration by hydrogen peroxide

In the water treatment field, activated carbons (ACs) have wide applications in adsorptions. However, the applications are limited by difficulties encountered in separation and regeneration processes. Here, activated carbon/Fe₃O₄ nanoparticle composites, which combine the adsorption features of powdered activated carbon (PAC) with the magnetic and excellent catalytic properties of Fe₃O₄ nanoparticles, were fabricated by a modified impregnation method using HNO₃ as the carbon modifying agent. The obtained composites were characterized by X-ray diffraction, scanning and transmission electron microscopy, nitrogen adsorption isotherms and vibrating sample magnetometer. Their performance for methyl orange (MO) removal by adsorption was evaluated. The regeneration of the composite and PAC-HNO₃ (powdered activated carbon modified by HNO₃) adsorbed MO by hydrogen peroxide was investigated. The composites had a high specific surface area and porosity and a superparamagnetic property that shows they can be manipulated by an external magnetic field. Adsorption experiments showed that the MO sorption process on the composites followed pseudo-second order kinetic model and the adsorption isotherm date could be simulated with both the Freundlich and Langmuir models. The regeneration indicated that the presence of the Fe₃O₄ nanoparticles is important for a achieving high regeneration efficiency by hydrogen peroxide.     

Comparison of land nitrogen budgets for European agriculture by various modeling approaches

A comparison of nitrogen (N) budgets for the year 2000 of agro-ecosystems is made for the EU 27 countries by four models with different complexity and data requirements, i.e. INTEGRATOR, IDEAg, MITERRA and IMAGE. The models estimate a comparable total N input in European agriculture, i.e. 23.3–25.7 Mton N yr⁻¹, but N uptake varies more, i.e. from 11.3 to 15.4 Mton N yr⁻¹ leading to total N surpluses varying from 10.4 to 13.2 Mton N yr⁻¹. The estimated overall variation at EU 27 is small for the emissions of ammonia (2.8–3.1 Mton N yr⁻¹) and nitrous oxide (0.33–0.43 Mton N yr⁻¹), but large for the sum of N leaching and runoff (2.7–6.3 Mton N yr⁻¹). Unlike the overall EU estimates, the difference in N output fluxes between models is large at regional scale. This is mainly determined by N inputs, differences being highest in areas with high livestock density.